1. Field of the Invention
The present invention relates to an image forming system and a method therefor for receiving image data generated substantially at a constant data rate, buffering the received image data so as to prevent underflowing, and forming an image.
2. Description of the Related Art
It is sometimes desired to connect a scanner apparatus and a high speed printer apparatus through a network to print (form) image data read by the scanner apparatus by the printer apparatus.
Such printing processing is also called “network distributed copy processing.”
In such a case, the image data transmitted by the scanner apparatus is received by the high speed printer apparatus, and once buffered (spooled) before printing.
In such a case, the high speed printer generally feeds output sheets very rapidly for printing, so that if image data underflows in the high speed printer apparatus, output sheets without printing can be discharged.
Therefore, conventionally, the high speed printer apparatus employs a method of receiving all image data, spooling the received image data and then starting printing.
When the method of the prior art technique 1 is employed to start printing after all image data has been received in this manner, the printing cannot be performed during the reception of the image data, as a matter of course.
Therefore, the operating rate of the high speed printer apparatus is reduced, and a longer time is required for the printing.
Also, for reducing a delay of starting the output while avoiding underflowing of data, the field of real time media transfer such as audio, moving image and the like, for example, may employ a method of measuring an input rate to a buffer before output processing to find a minimally required amount of anticipatory buffering for absorbing fluctuations in an output rate from the buffer.
However, this method does not ensure to avoid underflowing of data.
For example, even if underflowing occurs while a moving image is being displayed, this will cause disturbance or the like in an image without leaving the result as a specific object, so that the prior art technique permits more or less the occurrence of underflowing based on such an aspect.
On the other hand, if image data for a high speed printer apparatus underflows, a defectively printed output sheet is discharged as a specific object as a result of a failure due to the underflowing, for example, as shown in JP-A-Hei. 7-132666.
Therefore, the latter method cannot be applied to the network distributed copy.
The invention has been made in view of the aforementioned problems of the prior art, and it is an object to provide an image forming system and a method therefor which in an image forming apparatus before receiving all image data generated in an image generation apparatus.